But Beijing and Brussels have been preparing to announce their intention to accelerate joint efforts to reduce global carbon emissions.

According to a statement being prepared before an EU-China summit in Brussels on Thursday and Friday, the new alliance will say they are determined to “lead the energy transition” toward a low-carbon economy.

The EU’s climate commissioner, Miguel Arias Cañete, told the Guardian: “The EU and China are joining forces to forge ahead on the implementation of the Paris agreement and accelerate the global transition to clean energy.”

US would join Syria and Nicaragua on climate accord 'no' list

Read more

Cañete continued: “No one should be left behind, but the EU and China have decided to move forward. Our successful cooperation on issues like emissions trading and clean technologies are bearing fruit. Now is the time to further strengthen these ties to keep the wheels turning for ambitious global climate action.”

In their declaration, Brussels and Beijing will also call on all parties “to uphold the Paris agreement” and signal their “highest political commitment” to doing so themselves.

The document describes climate change as a “national security issue” and “multiplying factor of social and political fragility”. The Paris pact is a “historic achievement” and “irreversible”, the document says.

In a bid to calm jangling nerves in the developing world, the document reaffirms funding commitments and promises to bring forward new mid-century greenhouse gas reduction targets. The two blocs will also launch their first ever clean-energy cooperation, as well as measures on energy efficiency, low-emissions transport and low-carbon cooperation between cities.

“The EU-China agreement on the full implementation on international commitments under the Paris agreement becomes even more important,” one EU source said.

A senior EU official said there was a steely determination that the Paris agreement would not be allowed to unravel, having formally come into force last November. “This is not the end of the world,” she said.

What is the Paris agreement?

It's a climate change accord agreed by nearly 200 countries in December 2015, which came into force on 4 November 2016. The agreement commits world leaders to keeping global warming below 2C, seen as the threshold for safety by scientists, and pursuing a tougher target of 1.5C. The carbon emission curbs put forward by countries under Paris are not legally-binding but the framework of the accord, which includes a mechanism for periodically cranking those pledges up, is binding. The agreement also has a long-term goal for net zero emissions which would effectively phase out fossil fuels.

It is hoped that the opposition for action on climate change in the White House will not be matched at the state level, where programmes are already in place and where there is a political will to defy the Washington line.

The expected announcement in Brussels illustrates China’s determination to take a leadership role in the world as Trump turns the US inwards and prepares to shun its commitments under an international agreement Barack Obama had described as a “turning point for our planet” and a “major leap for mankind”.

The joint EU-China statement will offer a high level of detail on how they intend to make real the promises they made when they agreed to limit global warming to well below 2C (3.6F).

The EU, which has pioneered an emissions trading system, has agreed to provide China with €10m ($11.2m) to support its plan to roll out its own programme this year.

Both sides will also promise to help developing countries reduce their carbon footprint, and the EU will increasingly share its technological knowhow. “Tackling climate change and reforming our energy systems are significant drivers of job creation, investment opportunities and economic growth,” the joint statement is expected to say.

On Wednesday, reports emerged from Washington that Trump had, after months of prevarication, decided to remove the US from the agreement – despite pressure from world leaders at last weekend’s G7 summit. The speculation in the US was followed by a tweet from the president in which he said he would announce his decision “on the Paris accord over the next few days. MAKE AMERICA GREAT AGAIN!”

Chinese president Xi Jinping and European Commission president Jean-Claude Juncker in 2016. The EU-China document describes climate change as a ‘national security issue’. Photograph: Reuters

The expected decision from Trump – who once described climate change as a Chinese hoax – has appalled leaders in the EU and China, but there is a resolve to maintain the momentum behind the Paris agreement. EU sources said there was no evidence that any other countries would follow Washington’s lead.

In Denmark, the country’s climate minister, Lars Christian Lilleholt, said that “if true, this is a really, really bad signal from the United States.”

On Thursday night in Brussels, the Chinese prime minister, Li Keqiang, will join the president of the European council, Donald Tusk, and European Commission president Jean-Claude Juncker for an informal dinner before the main events the following day.

A series of communiques and memorandums of understanding are expected to be released. The issues range from a need to increase free trade and ensure respect for global rules and norms, to dealing with non-competitive practices.

The EU will also raise its continued concerns about human rights abuses in China, in particular in relation to new legislation on non-governmental organisations and the media.

China eyes an opportunity to take ownership of climate change fight

Read more

However it will be the joint climate change statement that will be the centrepiece of the summit. An EU official said: “The climate change discussions will be about how to promote the implementation of the deal in Paris. How to promote the use of clean energies.

“This is a survival question for many Chinese cities and regions. And also for India. Europe has unprecedented knowhow in this field – technological knowhow, and also legal and regulatory knowhow to promote the use of such technologies. This is therefore a key area of cooperation between us.”

Wendel Trio, the Director of Climate Action Network Europe said: “The summit shows that climate protection is and will remain top priority in the international cooperation, no matter what the US administration does.

“The strengthened climate alliance between the EU and China should trigger more climate action. This will smooth the way for the two powers to ramp up their Paris climate pledges by 2020, when they are due to be resubmitted. Both are set to overachieve their targets and can afford to make an even bigger contribution.”

Li Shuo, the climate policy adviser of Greenpeace East Asia, said it was crucial for the largest emitters of carbon to fill the vacuum left by the US’s likely decision.

He said: “The rapid backlash of US climate action requires enhanced leadership from all other countries. At the upcoming EU-China summit, Beijing and Brussels need to demonstrate they are putting new and collective leadership into concrete terms. If US-China climate cooperation gave birth to the Paris agreement, now it is up to EU and China to defend and enhance it.”